There is an intel® Server Chassis SC5600BRP with Intel® Server Board S5500HCV which supports RAID 1. We have done a RAID 1 with two H.D.D each having a capacity of 500GB and has been working for a while. We are planning to add 2 More H.D.D with capacity of one TB, in order to expand our storage capacity. With the knowledge that information stored on the two available HDDs are important and it is not acceptable to lose any data (and operating system), how could I do the fore mentioned upgrade.